Powder metallurgy



H. A. TOULMlN, JR

POWDER METALLURGY Sept. 4, 1945.

Filed July 3, 1944 INVENTOR HARRY A. TOULMIM E.

Patented Sept. 4, 1945 aims POWDER rm'raLLUaoy I Oakwood, Ohio, assignor Harry A. Touimin, Jr.,

to H-P-M Development Corporation, Wilmingon of Delaware ton, DeL, a corporati Application July 3, 1944, Serial No. 543,310

11 Claims.

This application is a continuation-in-part of copending application Serial No. 477,870, filed March 3, 1943.

The present invention relates to powder metallurgy, and more particularlydeals with the application of induction heat in powder metallurgy to produce articles at a greater rate of production than has been considered possible hitherto and without the necessity of a final sintering.

According to the present invention metal in powder form may be subjected to the action of a magnetic field and thereafter to the action of supersonic vibration prior to the pressing operation. The application of a magnetic field to the particles of metal in the mold cavity causes the alignment of the individual particles of powder metal in an even orderly arrangement and thereby facilitates the results which are obtained by subsequent steps in the process. Thereafter the magnetically arranged or magnetically aligned particles of powdered metals are subjected tov supersonic vibrations, and this causes a definite and substantial compacting of the metal powder by permitting the properly aligned particles to come together in the closest possible arrangement. The magnetically aligned and supersonically compacted particles of metal'are th' '1 subjected to a pressing operation to form a coherent compact body of any desired shape, and the resulting body is finally sintered by means which will be described hereinafter.

As a preferred alternative, the magnetically aligned and supersonically compacted particles of metal may be heated by means of induction heat within the moldcavity, and either concurrent therewith or immediately thereafter subjected to' pressure to yield a finished article which requires no sintering.

The metal powder in the mold cavity may be subjected to heating simultaneously with pressing or with subsequent pressing without necessarily subjecting it previously to magnetic alignment and supersonic compacting; however, these preliminary operations are found helpful and advantageous when a finished article of highest density is desired.

The present invention will be fully understood from the following description taken in connection with the annexed drawing wherein:

Fig. 1 is a diagrammatic representation of the first step of the method of the present invention wherein the particles of metal in the mold cavity are aligned perpendicularly:

Fig. 2 is similar to Fig. 1 and illustrates the is the movable alignment of the metal particles in the mold cavity horizontally;

Fig. 3 illustrates one mode in which high frequency vibration may be applied to the aligned particles of metal in the mold cavity;

Fig. 4 illustrates another mode in which high frequency vibrations may be applied to the aligned particles of metal in the mold cavity;

Fig. 5 illustrates the pressing operation which follows magnetic alignment and high frequency vibratory compacting of the metal particles in the mold cavity; and

Fig. 6 illustrates three modes in which pressed metal resulting from the operation of Fig. 5 may be sintered.

As will be explained more fully hereinafter,

heating of the metal powder in the mold cavity may take place simultaneously with the pressing operation illustrated in Fig. 5 or immediately preceding said pressing.

Referring now to the drawing in detail wherein like numbers are used toidentify like parts, I0 is the base of a press provided with a piston I I, I2 platen of the press provided with a piston I3, and It is a mold provided with a mold cavity I b.

Referring in particular to Fig. 1, i6 is a source of pulsating current from which leads I! carry current to elements I58 embedded in the mold It. In Fig. 1, the elements It produce magnetic fields I9 which cause the alignment in perpendicular relationship of the metal particles 20 in the mold cavity I 5; In Fig. 2 coils on opposite sides of the mold it create the magnetic fields 59' which are so arranged that the particles of metal in the mold cavity I5 are caused to align themselves in horizontal relationshi In Fig. 3, 2i is a sonic vibrator provided with leads 22 connected to a mounting 23 wherein there is set a quartz crystal 2d. The sonic vibrator 2| causes vibration of the quartz crystal 26 set in the mounting 23 and causes the particles of metal 20 in the mold cavity I5 further to align themselves with respect to each other and to become compacted. Y

In Fig. 28 are shown at the bottom and forming part of the platen i I on the press base.IB.- I v In Fig. 4 is illustrated an arrangement similar to that of Fig. 3 excepting that the quartz crystal 24 and its mounting 23 are shown above the mold cavity I5 and adapted to be withdrawn before the piston IS on the platen I2 is lowered 3 the quartz crystal 24 and its mounting of the mold cavity I5 I into the mold cavity 5 to compact the particles of metal 28 by forcing them against the face of the piston M on the press base Ill. In other words, after the magnetic aligning operation of Fig. 2, the quartz crystal t on the mounting 23 is placed adjacent the top of the mold cavity 15 to provide the required vibration and is withdrawn prior to the actual pressing operation.

Fig. illustrates the metal particles 26 being actually compressed between the piston l3 on the platen l2 and the piston H on the press base 10. If so desired, heat may be employed in the course of this pressing operation or immediately preceding said pressing, and such heat may be provided by any desired mea The block or body of compressed metal which results from the pressing operation illustrated in Fig. 5 may be sintered by any of the means illustrated in Fig. 6. For example, the block of metal 25 may be subjected to induction heating to cause sintering of the individual particles, the source of induction current being the leads 26, or the block of metal 25 may be sintered in a furnace 27 or by resistance heating between plates 28 provided with current from leads 29.

It will be understood that in Figs. 3, 4 and 5 the leads ii are inactive since they are solely employed in the operation (magnetic alignment) illustrated in Figs. 1 and 2.

As has been noted 'hereinbefore, heat may be employed in the course of illustrated in Fig. 5. The heating may serve for presintering and may be produced .by electroinduction or by any other suitablemethod which will give a temperature consistent .with the sinter-- ing point of the metal being molded. P

Those skilled in the art will understand that the method herein'descri ed and illustrated in the drawing may be applied to a varietyof metals. Obviously the step illustrated in Figs. 1 and 2 is applicable only to metals such as iron, cobalt and nickel which will respond to magnetic stimulus; however, the process herein described may be practiced with non-magnetic metals by causing the particles of metal to be both aligned and compacted by the application of supersonic vioration as illustrated in Figs. 3 and 4. In other words, the application of magnetic vibration to the particles of metal in the mold cavity is'beneficial and advantageous when the metal therein will respond to magnetic stimulus, but metals which are of nonemagnetic character may be successfully treated by the application of supersonic vibration alone.

It will be understood by those skilled in the art that the article formed in the pressing operation illustrated in Fig. 6 may be withdrawn from the mold cavity by withdrawing the piston Hi from the mold cavity l I to move upwardly into .the cavity l5 so as to lift the article but of the mold cavity. Another way of removing the article from the mold cavity I5 is by lowering the piston ll and causing the piston l3, to travel downwardly through the mold cavityl5, thus ejecting the article from the mold cavity. Other means of accomplishing the same purpose will be evident to those skilled in the art.

The great advantage of the invention claimed in this application lies in the fact that by the practice thereof it is possible to obtain finished articles by powder metallurgy without the necessity of subjecting the article, to a final sintering treatment. In other words, the metal powder is placed in the mold cavity and there heated conl5 and causing the piston the pressing operation current with the application of pressure or immediately preceding the application of pressure. This brings about a substantial reduction in the time required to produce articles from metal powder, and in addition yields articles of superior quality.

Those skilled in the art will-understand readily that the method comprising heating and pressing the metal powder in the mold cavity greatly increases the rate of production and will produce a more uniform density throughout the mass. These are marked advantages which represent a substantial improvement in the art of powder metallurgy.

It will be understood that I desire to comprehend such modifications and substitution of equivalents as may be considered to come within the spirit of this disclosure and the scope of the appended claims.

I claim:

l. The method of making articles from metal powder at least a portion of which is magnetic which comprises placing the said powder in a mold cavity, subjecting said powder in said mold cavity to a. magnetic field whereby to align the metal particles inpredetermined position, there- "after subjecting the po "'der to mechanical vibration whereby to compact the metal particles, thereafter heating the powder, and thereafter pressing the heated powder in said mold cavity toproduce a finished article.

2. The method of making articles from metal powder at least a portion of which is magnetic which comprises placing said powder in a mold cavity, subjecting said powder in said mold cavity to a magnetic field whereby to align the metal particles in a predetermined position, thereafter subjecting the powder in said mold cavity to mechanical vibration whereby to compact said powder, and thereafter simultaneously heating and pressing said powderin said mold cavity to produce a finished article.

3. The method of making articles from metal powder at least a portion of which is magnetic according to claim 1, wherein the powder in the mold cavity is heated by induction heat.

4. The method of making articles from metal powder at least a portion of which is magnetic according to claim 2, wherein the mold cavity is heated by induction heat.

5. The method of making articles from metal powder at least a portion of which is magnetic which comprises placing the said powder in a mold cavity, subjecting said powder in said mold cavity to a magnetic field whereby to align the metal particles in predetermined position, thereafter subjecting the powder to high frequency vibration whereby to compact the metal particles, thereafter heating the powder, and thereafter pressing the heated powder in said mold cavity to produce a, finished article.

6. The method of making articles from metal powder at least a portion of which is magnetic which comprises placing said powder in a mold cavity, subjecting said powder in said mold cavity to a magnetic field whereby to align the metal particles in a predetermined-position, thereafter subjecting the powder in said mold cavity to high frequency vibration whereby to compact said powder, and thereafter simultaneously heatin and pressing said powder in said mold cavity to produce afinished article.

7. The method of making articles irom metal powder at least a portion of which is magnetic powder in the mold cavity is heated by induction heat.

9. The method of making articles from mag netic particles which comprises placing the said particles in a mold cavity, creating a substantially axial magnetic field in said cavity whereby to align said particles in predetermined position, thereafter subjecting the aligned particles to high frequency mechanical vibration whereby at least partially to compact the same, compressingthe said particles and thereafter heating the compressed mass to sintering temperature.

10. The method'of making articles from mag netic particles which comprises placing thevsaid particles in' a. mold cavity, establishing a magnetic field-through said cavity in a transverse direction thereby to align said particles, thereafter subjecting the particles to high frequency mechanical vibration whereby at least partially to compact the same, and thereafter pressing and heating the particles in order to produce a compact, sintered workpiece. v

11. The method of making articles from particulate material at least a portion of which is magnetic which comprises placing the particles in a mold cavity, establishing a substantially unidirectional magnetic field through said cavitywhereby to align said particles, thereafter subjecting the particles to high frequency vibration whereby at least partially to compactthe same,

and thereafter applying heat and pressure to the said particles thereby to Produce a compact, sintered workpiece. Y

, HARRY'A'TOULMIN, JR. 

